linux-kernel - Re: [PATCH] fix integer overflow in groups

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-Id: <20100903165446.378e8ceb.akpm@linux-foundation.org>
Date:	Fri, 3 Sep 2010 16:54:46 -0700
From:	Andrew Morton <akpm@...ux-foundation.org>
To:	Jerome Marchand <jmarchan@...hat.com>
Cc:	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] fix integer overflow in groups_search

On Thu, 02 Sep 2010 17:20:20 +0200
Jerome Marchand <jmarchan@...hat.com> wrote:

> 
> gid_t is a unsigned int. If group_info contains a gid greater than
> MAX_INT, groups_search() function may look on the wrong side of the 
> search tree.
> This solves some unfair "permission denied" problems.
> 
> Signed-off-by: Jerome Marchand <jmarchan@...hat.com>
> ---
> diff --git a/kernel/groups.c b/kernel/groups.c
> index 53b1916..253dc0f 100644
> --- a/kernel/groups.c
> +++ b/kernel/groups.c
> @@ -143,10 +143,9 @@ int groups_search(const struct group_info *group_info, gid_t grp)
>  	right = group_info->ngroups;
>  	while (left < right) {
>  		unsigned int mid = (left+right)/2;
> -		int cmp = grp - GROUP_AT(group_info, mid);
> -		if (cmp > 0)
> +		if (grp > GROUP_AT(group_info, mid))
>  			left = mid + 1;
> -		else if (cmp < 0)
> +		else if (grp < GROUP_AT(group_info, mid))
>  			right = mid;
>  		else
>  			return 1;

hah, that's some pretty ancient code there.  You must have a lot of
groups.

The patch is a no-brainer and I guess you've encountered the bug in
real kernels so I think we'll wave the fix at the -stable guys for
backporting, OK?

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/